Eyelashes, in addition to their contribution to appearance, serve a functional role by protecting sensitive eye structures against foreign particles entering the eye. The nerve plexus that surrounds hair follicles has a very low threshold for excitation (Moses, 1970); as a result, dust or other particles that may come into contact with the eyelash hair fiber are sufficient stimuli to produce a blink reflex, thereby protecting the eye. In terms of the aesthetic function of eyelashes, eyelash prominence has been observed to be related to the attractiveness of individuals, with long, thick eyelashes considered to be a desirable physical attribute with a positive psychological effect (Shaikh and Bodla, 2006).
Inadequate or not having enough eyelashes is known as hypotrichosis of the eyelashes. Etiologies of hypotrichosis of the eyelashes in an adult population include idiopathic hypotrichosis, alopecia-inducing medication (e.g., chemotherapeutic agents) and underlying cutaneous or systemic diseases/conditions (eg, alopecia greata or hypothyroidism).
In healthy adults, eyelash hypotrichosis is often idiopathic and may be related to age. There is an inverse relationship between age and length of eyelashes; younger populations naturally tend to have longer eyelashes, while older populations tend to have shorter eyelashes (Pucci, 2005). For this reason, many otherwise healthy adults experience hypotrichosis as a consequence of aging.
A treatment is available for the natural hypotrichosis condition which may be result of person's genetic makeup or could be age related. Bimatoprost solution 0.03% (LATISSE®) is marketed for the treatment of hypotrichosis of the eyelashes. Bimatoprost is a synthetic prostamide. Topical application of bimatoprost solution can be used in normal healthy adults with inadequate amount of eyelashes or subject who want to further enhance the prominence of their eyelashes (Yoelin, 2010). Treatment with bimatoprost has been demonstrated to increase the percentage of eyelash follicles in anagen, which accounts for its ability to lengthen eyelashes. Bimatoprost-induced stimulation of melanogenesis in melanocytes present in dermal papilla which are responsible for hair shaft pigmentation results in darker eyelashes and, at the same time, appears to increase the size of the dermal papilla and hair bulb, affecting lash thickness and fullness (Cohen, 2010; Fagien, 2010; Law, 2010).
In contrast to the natural eyelash hypotrichosis condition where the hair follicle is normal except it produces shorter and inadequate amount of eyelashes, chemotherapy treatment results in damage to the hair follicle components that make the hair fiber such that after the chemotherapy drug treatment, the natural eyelashes either fall off completely or result in patchy hair loss. Chemotherapeutic agents are well known for their ability to cause hair loss. Other drugs that can cause hair loss to varied degrees include anticoagulants, antithyroid drugs, oral contraceptives, lithium, interferons, antihyperlipidemic drugs, and retinoids (Tosti et al, 1994). Chemotherapy-induced hair loss is known to result from the direct toxic insult to rapidly dividing cells of the hair follicle (Trueb, 2009). During the anagen phase of the hair cycle, the epithelial compartment of the follicle undergoes proliferation, with the greatest proliferative activity occurring in the bulb matrix cells as they build up the hair shaft. When cell mitosis abruptly ceases as a result of cytotoxic therapy, the partially keratinized hair shaft weakens and falls out, resulting in anagen dystrophic effluvium (Ulrich et al, 2008). In addition, some chemotherapeutic agents can cause apoptosis (ie, programmed cell death) in the follicular epithelium resulting in premature transitioning from anagen to catagen phases of the hair cycle; this process is known as telogen effluvium (Ulrich et al, 2008). The consequence of these processes is hair shedding, which can begin within 1 to 3 weeks and is often complete within 1 to 2 months after beginning chemotherapy (Trueb, 2009). Hair loss occurs with an estimated incidence of 65% in adult patients receiving chemotherapy (Trueb, 2009). While eyelash loss can be part of the experience of chemotherapy-induced hair loss (Trueb, 2009), there are no reliable data in the published literature that specifically address the incidence of eyelash loss due to chemotherapy. However, the known mechanism by which chemotherapy induces alopecia indicates that any active hair follicle in anagen would be susceptible, including scalp, body, eyebrow, and eyelash hair.
For most cancer treatments, after the chemotherapy regimen is completed, the patient recovers from the treatment side effects relatively quickly, ie, most side effects of chemotherapy resolve within a few weeks of the last treatment; however, hair growth can continue to be depressed for a period of time. It can take several months to a year, or even longer in some subjects, for hair growth to restore to pre-chemotherapy levels. Moreover, when the hair does recover early, it is generally much finer and thinner than the original hair and can take several hair cycles to restore to the pre-chemotherapy levels.
Hair loss is known to be one of the most psychologically upsetting side effects of cancer therapy (Botchkarev, 2003, Lemieux et al, 2008; Hunt, 2005); it has been described by patients as a constant reminder of their illness and is associated with a loss of control, an altered sense of self, and reduced social functioning (Beisecker et al, 1997; Cowley, 2000; Freedman, 1994; Luoma and Hakamies-Blomqvist, 2004; Richer and Ezer, 2002; Williams et al, 1999). The loss not just of scalp hair but body hair can lead to psychosocial problems such as diminished quality of life expressed as anxiety, depression, and low self-esteem (Ulrich et al, 2008).
In the focus group studies, patients stated that the loss of eyelashes and eyebrows was worse than the loss of scalp hair because the latter could be easily concealed by a wig, whereas there was no way to make their eyelashes look “normal”. False eyelashes were not a reasonable treatment in the opinion of the respondents because they did not have enough natural eyelashes to help the glue adhere to their eyelid margins. Moreover, such measures can result in severe irritation and skin damage and are therefore not ideal, especially in the post-chemotherapy population. In focus-group studies, many post-chemotherapy patients commented that their eyelashes never fully recovered to their pre-chemotherapy levels. Even though they noticed some re-growth, most complained that their eyelashes were sparse (ie, gaps between lashes), short, and lighter in color.
Currently there are no treatments available for chemotherapy induced eyelash loss. We discovered that treatment with LATISSE (bimatoprost 0.03% solution) restores eyelash growth and prominence quickly compared with the natural course of slower recovery. Thus the protective function of eyelashes is resumed earlier in treated patients as compared to non-treated patients. The post-chemotherapy patients treated with bimatoprost 0.03% solution express a higher overall satisfaction with their eyelashes as compared to patients treated with vehicle. Bimatoprost treatment in post-chemotherapy patients also restored length, thickness/fullness and darkness of eyelashes.